'Brain Pacemaker' Treats Primary Dystonia

Movement disorder has no known cause

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WEDNESDAY, April 16, 2003 (HealthDayNews) -- A brain implant to help control symptoms of a rare movement disorder called primary dystonia has been approved by the U.S. Food and Drug Administration.

The disorder causes various muscles to contract into abnormal and often painful positions. The Medtronic Inc. device, called the Activa Dystonia Therapy System, uses deep brain stimulation to suppress symptoms. Electrodes are implanted into the brain and connected by wires under the skin to a neurostimulator implanted in the chest.

The stimulator sends electrical impulses directly to the brain. To turn it on or off, a user touches a hand-held magnet over the neurostimulator.

The device has already been approved to treat two more common movement disorders -- Parkinson's disease and essential tremor. Wednesday's approval broadens its use to people with primary dystonia who get little or no relief with medication.

About 2,000 people a year in the United States are expected to be candidates for the device, the FDA says in a prepared statement. The agency gave its OK after reviewing 34 scientific studies showing the device's relative safety and potential benefits.

Approval was granted through a regulatory process known as a humanitarian device exemption -- designed to encourage production of innovative medical devices for patients with rare conditions that affect 4,000 or fewer people annually.